Winter expected to be dry despite recent showers
By Scott Nicholson
nicholson@wataugademocrat.com

Recent rains have helped raise water tables and dampen the threat of wildfire, but it’s going to take a lot more help from above to ease out of the drought.

A 2007-08 winter drought outlook issued by the National Weather Service and the N.C. Climate office predicts a dry winter and states much more precipitation will be needed to offset the extended dry period.

The report said the state received two to five inches of rain in late October, but the increases to lakes and river flows will not last the winter.

In fact, by the first week of November some major river flows were already back to their previous low levels despite the rainfall.

As of Nov. 4, 62 percent of the stream gages in the state were recording levels below the 25th percentile, meaning stream flow was below 25 percent of normal flow.

More than a third of the monitoring sites recorded new record lows and were below the 10th percentile in flow based on historic records dating back to the early 1900s.

With a record heat wave in the summer and dry conditions originating in the spring, climatologists believe recent water-level increases are only temporary.

Since July, rainfall has averaged below half of what is normally expected during the same period. Many lakes and reservoirs are experiencing “negative inflows,” meaning less water is coming in than is being lost through consumption and evaporation.

Public water sources like Falls Lake near Raleigh, Jordan Lake near Durham and Chapel Hill and the Kerr Scott reservoir in Wilkes County received some benefit from the rains but still are well below normal levels.

Drought conditions also contribute to the threat of wildfire, with a statewide burning ban remaining in place.

In addition to much of the state being under extreme or exceptional drought, the state is also in the most severe classification for fire danger.

According to the drought outlook, “Extreme droughts by definition occur about 4 percent or less of the time through the climatological record. This means in any given year there is only a 4 percent chance of an extreme drought. Even during extreme droughts, the impacts can vary based on the duration and the time of year.”

Though records are inexact, based on calculations North Carolina is in the worst drought conditions since 1895, surpassing 2002’s and 1925’s droughts.

The state would need between 14 to 18 inches of precipitation over the next three months, or 25 to 30 inches over the next six months, to ease the drought. That’s five to seven inches more than would be expected over a typical winter.

Climatologists also note the extra rain would not end the impact of dry weather, but only reduce the effects of the drought. The probability of that happening is between 10 and 15 percent, according to predictions.

The National Weather Service says the long-term outlook is for moderate rainfall over the winter.

The La Nina effect, part of a weather cycle based on sea-surface temperatures in the central Pacific Ocean, typically weakens the ability of the jet stream to carry moisture and storms into the Atlantic region and high pressure blocks the storm systems from reaching the northern portion of the country.

The latest precipitation outlook suggests “increased likelihood of receiving below normal precipitation across the southeast and an increased likelihood of above normal precipitation in the Midwest and Pacific Northwest.”

The report states: “When the influence of a moderate to strong La Nina impacts are combined with precipitation trends observed over the past 15 years, precipitation typically averages 3 inches below normal during winter months.” However, above-normal rains and major snow events have been recorded during La Nina winters, including the record snowfall of Jan. 25, 2000.

There’s also more to the drought than just what falls. The amount that goes back up into the clouds also factors into stream and lake levels: “The good news is cooler fall and winter days mean less water loss to evaporation along with decreased water demand…However, it is important to understand that due to exceptionally low lake levels and water shortages, even a return to near normal rainfall over the next three to six months may not bring an end to the current drought.

“If climate predictions come to fruition and the rains and snows of the winter and spring remain below normal, farms, cities and residences will be facing ongoing water shortages as we move into the summer months next year.”

Beech Mountain and Blowing Rock have already imposed mandatory water-use restrictions, and Boone has changed its ordinance to more easily impose restrictions. Watauga County is rated as suffering “Exceptional Drought” by the North Carolina Drought Management Advisory Council.